It's not a have to thing and in reality, will likely never happen. We're house shopping and one of the ones that we saw had this massive room. There's already a contract on the house, so I'm not holding my breath.

But if by some miracle it does go our way, I'd be forced to do something with it and thus my wheels started spinning. It probably won't happen, but it's fun to think about it.

There really isn't much benefit to having double the speakers. There would be no gain in quality, unless m80's sound better at lower volumes for some reason (hence the combination of two at the same level would sound better). You could actually hinder some aspects of quality depending on placement. The amount of added spl would be minimal with only a 3 dB increase which is close to the threshold of a noticable difference in level. A doubling of sound pressure generates a 3 dB increase in level.

I ran my 60s with my 80s for a little while way back when, pre-outed the 80s to an amp from the H/K and ran the 60s from the receiver....Wid thought I was nuts but I thought they sounded pretty darn good.

The 60s and 80s also made for a very nice looking set (double set?) of mains parked next to one another.